Have some aliens and their craft found a way to break into our dimension ; whereas ghosts, poltergeists etc.'re more Earthlike and limited ?

Agree...whereas our mind is unlimited. If you manage the out of body experience, your mind can go wherever you want. 

Uh, no.  And ghosts are imaginary.

As it would appear from recent military footage, that certainly does appear to be the case. And what I find so compelling is that the US government has more to lose by making such an announcement than it does to gain by doing so. I personally have been off and on the fence regarding the visitation by intelligent life from elsewhere in the universe, but when such claims and evidence is brought forth and provided to mainstream media, it really is difficult to discount or deny that they do exist and that they are visiting earth. Take care!